Recipe. Do the following.
- Throw $N$ random points $(x_0,y_0),(x_1,y_1),x_2,y_2),\cdots,(x_{N-1},y_{N-1})$ in the plane.
Define $(x_N,y_N)=(x_0,y_0)$ : enumeration is $\mod N$ .
- These points are joined in a number of ways to form a polygon with $N$ edges.
Define "a number of ways" as permutations $\pi$ of the vertex numbering. Vertex $(0)$
can be left in place without loss of generality.
- Select the polygon with minimal perimeter i.e. the smallest sum of the edges lengths:
$$\sum_{k=0}^{N-1}\sqrt{(x_{\pi(k+1)}-x_{\pi(k)})^2+(y_{\pi(k+1)}-y_{\pi(k)})^2}
= \mbox{minimum}(\pi)$$
Conjecture. Such a polygon does not self-intersect
Picture on the left: Area maximized (and self intersecting).
(Where the area of the polygon is defined as in
this answer)
Picture on the right: Perimeter minimized (same vertices).
Vertex numbering: digit on the left is original, digit on the right is permutation.
Can someone prove or disprove this conjecture?
See this answer